In the related art, there is a known microdissection method in which very small segments are cut out from a tissue section in order to perform tests of localized gene expression or the like in the tissue section (for example, see Patent Literature 1). The method of Patent Literature 1 requires large-scale equipment and well-developed skills.
On the other hand, there is a method employed as a similar method to that of Patent Literature 1, in which a base substrate such as a cover glass or the like is divided into a group of small pieces in advance; in this state, they are attached to an adhesive sheet that can be expanded, so as to be arrayed without gaps therebetween; a tissue section is attached on the group of small pieces; and the sheet is expanded to separate the small pieces from each other, thereby dividing the tissue section into segments along the outline of the individual small pieces. Here, the base substrate is manually divided by using a glass cutter in a state in which it is attached to the adhesive sheet, and thus, the group of small pieces are arrayed on the adhesive sheet without gaps therebetween. To divide the base substrate by using a glass cutter, first, grid-like grooves with spaces of several millimeters or less therebetween are made on the base substrate by using a glass cutter, and, subsequently, the base substrate is manually divided into small pieces along the grooves.